Four variable fuel tax models are investigated with respect to Alabama Highway Department operations. The Fixed Percentage Fuel Tax Model establishes the state gasoline tax as a constant percentage of the wholesale price of gasoline. The Price Index Economic Model pegs state fuel taxes to a ratio of price indexes. The Fuel Efficiency Tax Model relates the gasoline tax to the variables of Consumer Price Index and vehicle efficiency. The Sales Tax Model establishes a sales tax on the purchase of gasoline and motor fuel sold in the state. Estimates of the amount of revenue expected to be generated by each model are made. Advantages and disadvantages of each model are presented.